Re: Bifilar Again!
Hello John, > > I think, in the end, absolutely anything (or things) that cast a shadow(s) > on any surface (plane or not) can be used to describe a sundial!! However, > the markings get very complex. Agreed, (not to mention the maths)!! > Thus, to answer your question, the two threads or edges don't have to be > parallel to the dial plane to produce a dial. What most people understand > by a "classic" bifilar dial does have this feature though. It leads to dial > markings which can be sensibly described mathematically, and are logical to > look at. My personal view, for what it's worth is that we should reserve > the name for these cases, and describe the more exotic variants in specific > detail. > > Best regards, > > John I would concur with earlier postings then, suggesting that perhaps some further terminology might be useful. thanks for the clarification Sarah
Re: Bifilar Again!
Hello Sarah, The 2 threads or edges may be straight or curved and may have any orientation. As long as there are 2 shadows of which the intersectionpoint is used as the point where to read the dial I call the dial a bifilar dial. This is based on historical reasons as I wrote in another message. The original idea by Micknik was a dial with equiangular hourlines. New ideas with one curved thread and one straight thread give dials with parallel datelines or with parallel hourlines. Many other ideas are just for fun to show what happens with the patterns. Theoretical it is possible to use 2 curved threads or edges, however I never saw such a dial. With 1 curved thread a number of examples may be found in literature and even there is an example with 2 cylinders as shadowcasters. Best wishes, Fer. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E - Original Message - From: Sarah Edmondson-Jones <[EMAIL PROTECTED]> To: ; John Davis <[EMAIL PROTECTED]> Sent: Saturday, October 21, 2000 5:46 PM Subject: Re: Bifilar Again! > Hello John et al, > I'm still trying to come to grips with the possibilities that bifilar dials > offer. Is it necessary for the 'lines/wires/planes' that cast the shadow to > be parallel with the dial plate? > best wishes > Sarah Edmondson-Jones > >
Re: Bifilar Again!
Hello John et al, I'm still trying to come to grips with the possibilities that bifilar dials offer. Is it necessary for the 'lines/wires/planes' that cast the shadow to be parallel with the dial plate? best wishes Sarah Edmondson-Jones
Re: Bifilar Again!
Hello Claude, Micknik developed the bifilar dial in the 1920's. 2 straight threads, parallel to an horizontal plane, were used as shadow casters. He named this dial a bifilar dial. Also in German the word is bifilar, however the pronunciation is some different. For historical reasons I think it is important to keep this name for this kind of a sundial. In stead of 2 threads also 2 edges of planes may be used as shadow casters, but still I suggest to use the word bifilar dial. There is no fundamental change in the concept of the dial. In the 1970's and 1980's new dials appeared in which one of the threads or edges is no longer straight but has a curved shape to get other patterns for the lines on the sundial. To my opinion these dials still are bifilar dials because the principle isn't changed: the dial has to be read at the intersectionpoint of 2 shadows of 2 threads or edges. However, I realize that naming and classifying sundials is a difficult matter in gnomonics. Best wishes, Fer. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E - Original Message - From: Claude Hartman <[EMAIL PROTECTED]> To: sundial list Sent: Friday, October 20, 2000 1:06 PM Subject: Bifilar Again! > Many of you may remember a thread on this list in March of this year > about the "bifilar" name. (I tried to look for it on the AstroArchive > site but I > could not do a search for titles or keywords. The egroup site is much > better: http://www.egroups.com/group/sundial) > > There seems to be continuing concern for the use of this name. As > before, there seems to be no other reason to refer to these non-linear > gnomons as "bifilar" other than the total lack of any better > terminology! The new BSS glossary does not even list the term, > "bifilar". > > After much consideration, I think a better term would be "bi-gnomon". > > This would help relate to the use of "bifilar" which seems to have been > used since 1920 but improve and broaden the definition. As Chris Lusby > Taylor wrote: > >Many recent so-called bifilar sundials merely use the > >intersection of the shadows of two rather arbitrary lines/curves. > > We might use the term "intersecting gnomon" or "bi-style" except that it > seems clumsy. If we accept the definition of gnomon as any type of > shadow casting object, we have a description of the physical dial. > > My thanks to Frans Maes for the posting of more views of the Appingedam > dial and the English translation. He has produced a very richly > illustrated site with valuable references. > > Claude Hartman > 35N 120W > >
Re: Bifilar Again!
Hi Claude, You wrote: >The new BSS glossary does not even list the term, > "bifilar". This is not so - it is there under "dial types", and reads: bifilar ~: invented in 1922 by Hugo Michnik in its horizontal form, although it can be on any plane. The time is indicated by the intersection on the dial plate, of the shadows of two wires (or other lines in space) stretched above and parallel to it. The wires often run E-W and N-S, with their (different) heights above the plane being a function of the location of the dial. It may have equiangular hour markings, and hence can be delineated to show many kinds of hours. Whilst we might discuss whether the definition needs extending to cover non-straight wires, I think this covers the most usual forms, Regards, John Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
Re: Bifilar Again
Hello Claude, Indeed, if we had to choose a new word for these kind of dials "bi-style" or "double style" would be a good choice. ( And then also "mono-style" if only one style is present as a pole style or vertical style or irregular style ) But the bifilar dial was invented by Michnik in the 1920's and he used the German words "bifilar Sonnenuhr". Because of this historical event I strongly vote for the original term bifilar dial. Fer. Fer J. de Vries [EMAIL PROTECTED] http://www.iae.nl/users/ferdv/ Eindhoven, Netherlands lat. 51:30 N long. 5:30 E - Original Message - From: Claude Hartman <[EMAIL PROTECTED]> To: sundial mailing list Sent: Thursday, March 02, 2000 8:04 PM Subject: Bifilar Again > "Bi-filar" seems to be used for > want of a better term. Perhaps > "bi-style", "duo-style" or "double > style" would be > better when referring to the > intersection of > two shadows. > > One example was described by Gianni > Ferrari: > > Another example was shown at the Reutte, > > Austria, sundial competition in 1998. > This was submitted by Rafael Soler and > called a "Bi-Filar" sundial. It marked > time by the intersection of the shadow > of a horizontal disk and its vertical > support rod. > > Attached is a small photo of this novel > design. A larger photo is in my report > of the > Reutte competition at the 99 NASS > Conference on > the NASS web site: www.sundials.org > > Claude Hartman > 35N 120W >
Re: Bifilar Again
On Thu, 2 Mar 2000, Claude Hartman wrote:
> Another example was shown at the Reutte,
> Austria, sundial competition in 1998.
> This was submitted by Rafael Soler and
> called a "Bi-Filar" sundial. It marked
> time by the intersection of the shadow
> of a horizontal disk and its vertical
> support rod.
>
> A larger photo is in my report
> of the Reutte competition at the 99 NASS
> Conference on the NASS web site:
http://www.sundials.org/conference/confpix/c-soler_m1.jpg
This is a very interesting dial design! As Claude described it, the
disk-shaped "hat" and the vertical shaft form the two edges of a bifilar
style. I can see how this could also be implemented as a single vertical
pole, with an overhanging "roof", the roof edge and pole casting their
shadows on the back wall of a porch or verandah, either vertical or sloped
as is Soler's dial plate.
Fer or Gianni: Would it be possible to include a more general sort of
bifilar dial design in your program(s)? Fer's Zonwvlak computes bifilar
designs, but assumes the threads are parallel to the X and Y axes, and (I
think) intersect the Z axis. Gianni's only accepts a single thread, but
allows it to be defined by two arbitrary (XYZ) points. A combination of
the two would be really, really nice!! :{)
Dave Bell
W121.9N37.3
